Saturday, February 4, 2012
Weekly SkyWatcher’s Forecast – February 5-11, 2012
Greetings, fellow SkyWatchers! At the beginning of this week we’ll enjoy lunar studies, but we’ll be hunting galaxies in Lepus before it ends! There are planets and more to explore, so get out your telescopes and binoculars, because here’s what’s up!
Sunday, February 5 - On this day in 1963, Maarten Schmidt measured the first quasar redshift and in 1974 the first close-up photography of Venus was made by Mariner 10. Tonight the great Grimaldi, found in the central region of the Moon near the terminator is the best lunar feature for binoculars. This huge, old basin on the western limb comes from the pre-Nectarian geological period and is definitely at least 4 billion years old. Spanning about 134 miles in diameter and filled with low albedo lava, Grimaldi - like Plato - is a landmark feature that's easily noticed even without optical aid, but holds wonderful details for study.
Using a telescope, take a look at the inner walls of Grimaldi, where you'll see they have been heavily eroded and worn away by impacts and time. All that's left now is a series of low hills and ridges – there are no sharp crater walls to distinguish it. Beyond the basin, an outer wall still remains. If the lighting is right at your time of observation, you'll notice it appears more strongly to the north and west, as opposed to the southeast Rimae Grimaldi. Take a close look at the floor region, too. It's home to a mascon – as well as lunar transient phenomena. Can you spot Lohrmann crater to its north or Riccioli crater to the southeast?
Let's begin our journey – and southern constellation studies - into Lepus as we take a look at Alpha. Its name is Arneb and it is a quality double star that resides around 900 light-years distant. Arneb's 11th magnitude disparate companion will take a larger scope to resolve. Its wide separation of 35.5" means it is probably not a true physical companion, but it is a challenge worthy of your time.
Monday, February 6 - On this day in 1971, astronaut Alan Shepherd became the first "lunar golfer” as he teed off on the Moon's surface. Think the ball is still in orbit? Then think again as his shot made a successful "hole in one” in a crater tens of meters away! If you haven't had a chance to view the Apollo 14 landing site, then try again when the Moon rises. You'll find it about midway along the bright peninsula-like feature that extends into Mare Nubium from the north. Return to landmark crater Grimaldi on the lunar surface tonight and we’ll continue our journey of evolution as we have a look at another walled plain just to the south - Darwin. Named for English naturalist Charles Darwin, this equally old feature bears the scars of the impact the created the Orientale Basin. Look carefully at the slopes in the northeast, for this may very well be material that was thrown there and left to slide back down to the crater floor. Spanning around 130 kilometers in diameter, Darwin’s actual size is only diminished by the fact that we view it on a curve. Its northern and southern shores have almost completely eroded, yet evidence remains of its eastern margin broken by the Rima Darwin which stretches for 280 kilometers. Was there lava here as well? Yes. Evidence still exists in the form of a dome along Darwin’s battered western edge. If the lighting is right, look at the western edge of Darwin for the Montes Cordillera. This is the external mountainous ring of Mare Orientale, and they could range as long as 545 miles in length, 182 miles in width and 18,200 feet in height. Many of the summits reach as much as 5000 feet! Talk about joining the mile high club...
Since the bright Moon will negate deep sky studies, let's celebrate the fiery return of the Soviet Space Station Salyut 7. Launched into orbit in 1982, the space station was doomed by electrical and maneuvering problems. At the time, cosmonauts would remain as long as eight months before returning to Earth. The project was abandoned in 1986, but some of the equipment and supplies were transferred to the orbiting Mir. On this day in 1991, Salyut re-entered our atmosphere and was lost. Have you ever wondered if you can spot orbiting spacecraft? Yes, you can. Many objects are visible to the unaided eye if you know where and when to look. Try checking with heavens-above.com for highly accurate information for your specific area. Many events are wonderful to witness. Among the most spectacular is the Iridium flare - the Sun reflecting off the highly polished sides of a communications satellite. Watching the ISS fly-over is also a wonder to behold! Try it tonight...
Tuesday, February 7 - On this day in 1889, the first national astronomy organization in the USA was born - the Astronomical Society of the Pacific. Congratulations to these fine people who continue to contribute to public astronomy awareness! We appreciate you… and the Night Sky Network! Tonight is Full Moon! During the month of February in the northern hemisphere is usually heavy in snow in the upper regions. Native Indian tribes of the north and east most often called February's full Moon the Full Snow Moon. Some tribes also referred to this Moon as the Full Hunger Moon. This is very understandable since the Arctic weather conditions in their areas made hunting very unproductive.
Although the skies will be bright tonight, let's return again to Lepus and an even more challenging double star - Beta. At a distance of 115 light-years, only a large telescope can hope to achieve an 11th magnitude companion no more than 2.5" distant. No luck? Then try your hand at 29 light-year distant Gamma. Even a very small telescope can easily split this colorful pair. The 3.5 magnitude primary star has a slightly yellow hue, while the 6.1 magnitude secondary appears more red-hued. Now it’s time for a star of singular beauty. Located about three fingerwidths southwest of Rigel, or a little more than a fingerwidth northwest of Mu in the constellation of Lepus, is R Leporis - better known as "Hind's Crimson Star”. Discovered in October of 1845 by J. R. Hind, R Leporis will require optical aid to view since it is a Mira-type variable that moves from approximately magnitude 6 to as low as magnitude 11 in about 432 days. As a carbon star, this particular example is well worth viewing for its intense ruby color when near minimum. As R Leporis undergoes its changes, it produces amazing amounts of carbon. To understand what makes it dim, think of an oil lamp. As the carbon "soot” collects on the glass, like the star's outer atmosphere, the light decreases until it is sloughed off and the process is repeated. At a rough distance of approximately 1500 light-years, Hind's Crimson Star will become an observing favorite and is also a challenge on many lists. Enjoy!
Heads up for Southern Hemisphere observers, over the next two nights will be the peak of the Centaurid meteor shower. Discovered by Michael Buhagiar of Australia, this stream has two radiants - Alpha and Beta. While both occur at roughly the same time and roughly from the same place, tonight's Alpha peak has a regular fall rate of around 3 per hour and an average magnitude of 2.4 while tomorrow's Beta stream varies with up to 14 per hour and far brighter at magnitude 1.6. Enjoy!
Wednesday, February 8 - Today celebrates the discovery of the Sayh al Uhaymir 094 "Mars Meteorite”. Found this day in 2001, scientists had long known Mars' surface was home to many impact craters which may have caused space-born debris. It was only a matter of time before a bit of this debris would be captured by Earth's gravity and be brought down as a meteorite. Upon study, tiny gas deposits were discovered in its composition that nearly matched the atmosphere of Mars as measured by the Viking Landers, and its mineral composition also leads science to believe the meteor originated from Mars.
Now, return to Beta Lepus and look west for Epsilon. Forming an isosceles triangle to the south is faint star ADS 3954 - also a closely matched double star. You will find M79 (Right Ascension: 5 : 24.5 - Declination: -24 : 33 ) just about a fingerwidth northeast. Originally discovered by Mechain in October of 1780, Messier himself didn't get around to looking at one of the very few globular clusters of winter until December of that year. On a good night, this small "round fuzzy” can be spotted with binoculars as an AL challenge object, but truly takes a telescope to appreciate. Moving away from us at 303 kilometers per second (188 miles per second), the 8th magnitude M79 will show as a concentrated ball of unresolvable stars to small aperture and begin resolution with larger scopes. At around 42 light-years away, this often over-looked Messier object is one of the very few globular clusters that resides further out in Milky Way galaxy than our own solar system!
Thursday, February 9 - Tonight we’ll begin early – and we’re going to use the telescope on Venus for a very good reason… Uranus is less than .2 degrees away to the south! For those of you who have never seen Uranus, this will be an awesome pairing that you’ll never forget. While Venus’ glare will be somewhat blinding, you might try using a light green, light blue or polarizing filter to help dim the situation. However, using a filter will also dim Uranus, too. Once you have them centered, try moving Venus out of the edge of the field of view. Who knows? You might not even need to!
Before Moon rise, return to the constellation of Lepus. For binoculars and small scopes, hop due east of Alpha Lepus about a fingerwidth for a brilliant multiple star system that is also designated as an open cluster - NGC 2017 (Right Ascension: 5 : 39.4 - Declination: -17 : 51 (degrees). First cataloged by Sir William Herschel at the Cape of Good Hope, this interesting group of stars will show in the same field as Alpha Leporis in binoculars, but come to colorful life in the telescope. The stars in this small open cluster are all gravitationally bound to each other and are a well-studied source of both radio and infrared emissions. NGC 2017 produces a dense wind from a thin H II region hidden within it, which may be from a loose distribution of gas and dust. Power up. As aperture increases - so does resolution. Watch as the primary colorful members begin to split into disparate pairs as magnification increases. It's a much underrated jewel box!
With the Moon absent from early evening skies, it's time to get more serious about Lepus and do some galaxy hunting. Our first marks will be Mu Leporis and NGC 1832 (Right Ascension: 5 : 12.1 - Declination: -15 : 41) in the same field to its north. At a rough magnitude of 12, this small galaxy isn't for the small scope, but is reasonably bright and easy to study with aperture. As an ongoing study for spiral arm pattern, rotation rates and star forming, a supernova incident was discovered in 2004 by LOSS and Federico Manzini. Look for a slightly oval shape that orients from north to south and brightens towards the core. A faint star can be seen at the edge of the arm structure to the northeast and it is best at mid-magnifications. Our second hop takes us about one degree southeast of Beta and into a stellar field for NGC 1964 (Right Ascension: 5 : 33.4 - Declination: -21 : 57). At a visual magnitude of 10.8, this Herschel 400 galaxy shows an oval disc elongated from the northeast to southwest with a bright core area and several faint stars that overlay the galaxy but are not involved with it. It can be spotted with scopes as small as 4.5", but truly requires larger aperture to appreciate.
Is the Moon rising yet? If so, you might want to stick around for awhile for a splendid conjunction with Mars!
Friday, February 10 - With early dark skies still in our favor, let's continue on through our tour of Lepus and the galaxy hunt. Tonight we'll go from one corner to the other as we begin with Iota and hop 2 degrees west for NGC 1784 (Right Ascension: 5 : 05.4 - Declination: -11 : 5). At magnitude 11.8, this barred spiral can be spotted in mid-aperture scopes as a misty oval with a slightly brighter center. With larger telescopes and optimal conditions, the central bar structure can be revealed as an elongated brightness towards the core region with some brighter knots noted in the arms. In studies done by Doug Ratay in radio wavelengths, NGC 1784 was mapped for its distribution of hydrogen gas both within and outside the galaxy structure. His incredible findings showed an orbiting area of gas that could be a small galaxy located about 100 million light-years away.
Our second mark is slightly more than more than 3 degrees south-southwest of Epsilon - NGC 1744 (Right Ascension: 5 : 00.0 - Declination: -26 : 01). Despite seeming to be possible - its magnitude is 12.3 - this north/south inclined barred spiral is anything but easy from the Northern Hemisphere - or the South! Very low surface brightness means this particular galaxy is a tough customer even for large telescopes and at best will show as a thin, nebulous area with no definition.
Saturday, February 11 - On this day in 1970 Lambda 4S-5, the first Japanese satellite, was launched. Tonight let's continue onward with deeper studies in the constellation of Lepus as we take on three galaxy challenges very worthy of the most seasoned amateur astronomer. Our goal area lies about a fistwidth southeast of Alpha Leporis as we start the hunt. The first galaxy, NGC 2179 (RA 06 08 02.10 Dec -21 44 48.0) holds an average magnitude of 13 which puts it in large telescope range, but does not make it easy. This very small galaxy will show as nothing more than a faint, round contrast change with some concentration towards the nucleus. It is bracketed on either side by stars and at lower power will show a slightly yellow and blue double star in the field. While this galaxy doesn't seem particularly spectacular, it contains one of the most massive dark matter halos so far discovered!
Next up is NGC 2196 (RA 06 12 10.00 Dec -21 48 24.0). At magnitude 12.6, this spiral is much larger and much brighter than our last. It is very round and shows some concentration towards the core that disappears at higher magnifications. Achievable in mid-sized telescopes, this particular galaxy is a lopsided spiral that shows gas accretion in its disc. Before we leave the area, let's have a look at NGC 2139 (RA 06 01 07.90 Dec -23 40 21.3). Holding a magnitude of 12.2, this peculiar spiral is also a faint object to detect. It's small, evenly dispersed, and better seen at lower powers along with the apparent double in the field. Keep an eye on this Seyfert, there was a supernova event in 1995!
Written by Tammy Plotner. If you'd like to know what's up for a full year, then check out her new book, the Night Sky Companion 2012!